In general, an ADE satellite antenna for transmitting and receiving a satellite frequency band signal of a C-band transmits and receives a satellite signal by installing a feeder (referred to as a feeding horn) at the position of a focus on which radio waves is collected by being reflected on a parabola dish in a prime focus scheme or a cassegrain scheme by using a parabola dish having a diameter of 1.2 m or more.
Since the band of the C-band uses a relatively low frequency of 3.4 to 6.725 GHz, the sizes of the parabola dish and the feeder need to be increased for a high gain of an antenna used for communication.
Further, in order to apply the prime focus and cassegrain scheme antennas having a comparatively smaller size than the known antenna, the size of the feeder is increased. That is, since the size of the feeder is increased, when the parabola dish is small, the feeder covers the parabola dish.
Further, when bi-directional communication is performed using the feeder, a polarizer for forming polarized waves and an orthogonal mode converter separating polarized waves of transmission and reception bands need to be provided. Therefore, manufacturing and installing processes are complicated and cost much.
Further, at present, a small-sized linearly polarized antenna system using a code division multiple access (CDMA) communication scheme has been developed. However, miniaturization of a circularly polarized antenna system should meet wideband characteristics such as an axial ratio and a gain and interference between transmission and reception antennas should be minimized. Therefore, there are many limits in development.